The present invention relates to nonwoven elastomeric web material and, particularly, to nonwoven fibrous elastomeric web material including meltblown elastic webs, with or without various types of fibers. More particularly, the present invention relates to meltblown elastic webs made cloth-like by hydraulically entangle bonding them, either by themselves or with various types of fibrous material and composites, such as pulp fibers (synthetic and natural pulp fibers, including wood pulp fibers), staple fibers such as vegetable fibers, cotton fibers (e.g., cotton linters) and flax, etc., other meltblown fibers, coform materials, and continuous filaments. Moreover, the present invention is directed to methods of forming such nonwoven elastomeric web material. These materials have a wide range of applications, from cheap disposable cover stock for, e.g., disposable diapers to wipes and durable nonwovens.
It has been desired to provide a nonwoven elastomeric material that has high strength and isotropic elastic properties, and that is cloth-like and has smooth surfaces, having good feel and drape.
U S. Pat. No. 4,209,563 to Sisson discloses a method of making an elastic material, and the elastic material formed by such method, the method including continuously forwarding relatively elastomeric filaments and elongatable but relatively non-elastic filaments onto a forming surface and binding at least some of the fiber crossings to form a coherent cloth which is subsequently mechanically worked, as by stretching, following which it is allowed to relax; the elastic modulus of the cloth is substantially reduced after the stretching resulting in the permanently stretched non-elastic filaments relaxing and looping to increase the bulk and improve the feel of the fabric. Forwarding of the filaments to the forming surface is positively controlled, which the patentee contrasts to the use of air streams to convey the fibers as used in meltblowing operations. Bonding of the filaments to form the coherent cloth may utilize embossing patterns or smooth, heated roll nips.
U.S. Pat. No. 4,426,420 to Likhyani discloses a nonwoven fabric having elastic properties and a process for forming such fabric, wherein a batt composed of at least two types of staple fibers is subjected to a hydraulic entanglement treatment to form a spunlaced nonwoven fabric. For the purpose of imparting greater stretch and resilience to the fabric, the process comprises forming the batt of hard fibers and of potentially elastic elastomeric fibers, and after the hydraulic entanglement treatment heat-treating the thus produced fabric to develop elastic characteristics in the elastomeric fibers. The preferred polymer for the elastomeric fibers is poly (butylene terephthalate)-co-poly-(tetramethyleneoxy) terephthalate. The hard fibers may be of any synthetic fiber-forming material, such as polyesters, polyamides, acrylic polymers and copolymers, vinyl polymers, cellulose derivatives, glass, and the like, as well as any natural fibers, such as cotton, wool, silk, paper and the like, or a blend of two or more hard fibers, the hard fibers generally having low stretch characteristics as compared to the stretch characteristics of the elastic fibers. This patent further discloses that the batt of the mixture of fibers that is hydraulically entangled can be formed by the procedures of forming fibers of each of the materials separately, and then blending the fibers together, the blend being formed into a batt on a carding machine.
U.S. Pat. No. 4,591,513 to Suzuki et al discloses a fiber-implanted nonwoven fabric, and method of producing such nonwoven fabric, wherein a fibrous web consisting of fibers shorter than 100 mm is laid upon a foamed and elastic sheet of open pore type having a thickness less than 5 mm, with this material then being subjected to hydraulic entangling while the foamed sheet is stretched by 10% or more, so that the short fibers of the fibrous web may be implanted deeply into the interior of the foamed sheet and not only mutually entangled on the surface of the fibrous web but also interlocked with material of the foamed sheet along the surface as well as in the interior of the foamed sheet. The short fibers can include natural fibers such as silk, cotton and flax, regenerated fibers such as rayon and cupro-ammonium rayon, semi-synthetic fibers such as acetate and premix, and synthetic fibers such as nylon, vinylon, vinylidene, vinyl chloride, polyester, acryl, polyethylene, polypropylene, polyurethane, benzoate and polyclar. The foamed sheet may be of foamed polyurethane.
U.S. Pat. No. 3,485,706 to Evans discloses a textile-like nonwoven fabric and a process and apparatus for its production, wherein the fabric has fibers randomly entangled with each other in a repeating pattern of localized entangled regions interconnected by fibers extending between adjacent entangled regions. The process disclosed in this patent involves supporting a layer of fibrous material on an apertured patterning member for treatment, jetting liquid supplied at pressures of at least 200 pounds per square inch (psi) gauge to form streams having over 23,000 energy flux in foot-pounds/inch.sup.2. second at the treatment distance, and traversing the supported layer of fibrous material with the streams to entangle fibers in a pattern determined by the supporting member, using a sufficient amount of treatment to produce uniformly patterned fabric. (Such technique, of using jetting liquid streams to entangle fibers in forming a bonded web material, is called hydraulic entanglement.) The initial material is disclosed to consist of any web, mat, batt or the like of loose fibers disposed in random relationship with one another or in any degree of alignment. The initial material may be made by desired techniques such as by carding, random lay-down, air or slurry deposition, etc.; and may consist of blends of fibers of different types and/or sizes, and may include scrim, woven cloth, bonded nonwoven fabrics, or other reinforcing material, which is incorporated into the final product by the hydraulic entanglement. This patent discloses the use of various fibers, including elastic fibers, to be used in the hydraulic entangling. In Example 56 of this patent is illustrated the preparation of nonwoven, multi-level patterned structures composed of two webs of polyester staple fibers which have a web of spandex yarn located therebetween, the webs being joined to each other by application of hydraulic jets of water which entangle the fibers of one web with the fibers of an adjacent web, with the spandex yarn being stretched 200% during the entangling step, thereby providing a puckered fabric with high elasticity in the warp direction.
U.S. Pat. No. 4,426,421 to Nakamae et al discloses a multi-layer composite sheet useful as a substrate for artificial leather, comprising at least three fibrous layers, namely, a superficial layer consisting of spun-laid extremely fine fibers entangled with each other, thereby forming a body of a nonwoven fibrous layer; an intermediate layer consisting of synthetic staple fibers entangled with each other to form a body of nonwoven fibrous layer; and a base layer consisting of a woven or knitted fabric. The composite sheet is disclosed to be prepared by superimposing the layers together in the aforementioned order and, then, incorporating them together to form a body of composite sheet by means of a needle-punching or water-stream-ejecting under a high pressure. This patent discloses that the spun-laid extremely fine fibers can be produced by a meltblown method.
While the above-discussed documents disclose products and processes which exhibit some of the characteristics or method steps of the present invention, none discloses or suggests the presently claimed process or the product resulting therefrom, and none achieves the advantages of the present invention. In particular, notwithstanding the various processes and products described in these documents, it is still desired to provide a nonwoven elastomeric web material having high strength and isotropic elastic properties, and which can have a smooth, cloth-like surface. It is further desired to provide such a nonwoven elastomeric web, wherein different texture and patterning properties can be achieved. Furthermore, it is also desired to provide such material, utilizing a process which is simple and relatively inexpensive.